Auto Technical Reference Library
Auto Refinishing: General Refinish Procedures
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Acid spotting is caused by atmospheric contamination. This contamination creates obvious discolored or surface altering spots on the painted surface. Industrial pollution is the major cause for acid spotting.
There are other types of acid related damage that can occur. Bird droppings, eggs and vehicle fluids are just a few examples of acid damage.
Neutralizing with a mixture of water and baking soda or detergent is the first step which should be performed when repairing acid spotting. Following the first wash, a vinegar bath is then performed. This should be performed as soon as possible following contamination to prevent the acid from penetrating further into the finish.
After the neutralizing process, a clay system may be used to further remove acid spotting. This clay system is a topcoat safe treatment to remove overspray, light acid rain, industrial fallout, water spotting, and brake and rail dust. This system uses a water-based lubricant contained in a spray bottle and a bar of clay. It is stored in an air tight container. The lubricant is sprayed on the damaged area. Using light pressure, the clay is hand rubbed over the area until all contaminants have been removed. The surface is then wiped with a clean, dry cloth.
Mild acid spotting can also be removed by wet sanding using a 1500 to 2000 grit sandpaper to remove imperfections. This is followed by low speed buffer and light compound to remove the fine scratches. Use of a high speed buffer is more aggressive, and may require hand polishing after buffing to remove swirl marks.
Sanding and refinishing may be required if the acid spots penetrated deep into the finish.
If contamination has reached the metal, plastic or factory primer, the spot must be stripped of paint materials before refinishing.
Acid Spotting Repair (Sanding and Refinishing)
Note: Refer to "Refinish Repaired Existing/Recycled Panel" and "Refinish New/Recycled Undamaged Panel" for a full description of steps.
1. Neutralize (wash with required materials)
2. Obtain Paint Code
3. Mix Color
4. Solvent Wash
5. Wet or Dry Sand
6. Dust or Water Removal with Air
7. Mask to Paint and Cover Remainder of Vehicle
8. Final Solvent Wash
9. Tack Wipe
10. Mix and Apply Sealer (if needed)
11. Mix and Apply Basecoat
12. Mix and Apply Midcoat
13. Mix and Apply Single-Stage Color
14. Mix and Apply Clearcoat (as required, add flex additive for plastic)
